Hydraulic chucks and arbors



United States Patent 3,250,542 HYDRAULIC CHUCKS AND ARBORS Franklyn E.Winnen, Cleveland, and David D. Walker,

Chagrin Falls, Ohio, assiguors to Erickson Tool Company, Solon, Ohio, acorporation of Ohio Filed May 4, 1964, Ser. No. 364,367 9 Claims. (Cl.279-4) The present invention relates generally as indicated to hydraulicchucks and arbors and, more particularly, to a chuck or holding deviceof the hydrostatic type in which pressure applied on oil'or greaseconfined in an annular chamber in the device is etfective to elasticallydeform a relatively thin Wall of the chamber into gripping engagementwith a workpiece, tool, or the like therewithin or therearound.

In known devices of this type, the outer wall of the annular chamber isconstituted by a relatively thin metal sleeve which has its ends weldedaround the body of the holding device. Said sleeve is thus sealed andsecured at its ends to the body to preclude leakage of the hydrostaticfluid and the portion of the sleeve between its ends is radiallyexpanded upon exertion of pressure on the hydrostatic fluid. Weldedjoints of this type suffer a disadvantage in that the welding operationproduces expansion due to the heat of welding, and moreover, thesubsequent shrinkage which occurs is apt to weaken the joints at thezones of welding. The welding operation also causes deformation of theparts of the holding device with resultant strains therein when theassembly cools to ambient temperature.

Itis an object of this invention to provide a hydrostatic chuck orholding device of the character in which the deformable sleeve issecurely mounted in the body of the holding device without welding, andin such manner that packing rings of rubber-like material may beemployed to preclude leakage of the hydrostatic fluid through the jointsbetween the telescopically interfitting sleeve and body.

It is another object of this invention to provide a hydrostatic chuck orholding device in which the aforesaid deformable sleeve is so fashionedand mounted that there is no perceptible deformation of the sleeve inthe areas of the aforesaid packing rings whereby no leakage of thehydrostatic fluid can occur in use of the holding device, and that thedeformation of the sleeve occurs uniformly along a major portion of thelength thereof to provide for firm and stable gripping of a work-piece,tool, or the like.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawings setting forth in detain-certain illustrativeembodiments of the invention, these being indicative, however, of but afew of the various ways in which the principle of the invention may beemployed.

In said annexed drawing:

FIG. 1 is a longitudinal cross-section view of one form of chuck orholding device taken susbtantially along the line 1-1, FIG. 2;

FIG. 2 is a transverse cross-section view taken substantially along theline 22, FIG. 1;

FIG. 3 is a much enlarged fragmentary radial crosssection view showingthe manner in which the gripping sleeve deforms upon application ofpressure on the hydrostatic fluid confined in the annular chamber of thepresent chuck or holding device;

FIG. 4 is a fragmentary radial cross-section view showing a modifiedform of sleeve mounting;

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FIG. 5 is a transverse cross-section view showing a modified form ofplunger for applying pressure on the hydrostatic fluid;

FIG. 6 is a fragmentary radial cross-section view show ing another formof gripping sleeve; and

FIG. 7 is a diametral cross-section view of an arbor or mandrel.

Referring now more particularly to the drawing, the referring numeral 1denotes the body of the chuck which is provided with a pilot 2 and amounting flange 3 by which the same may be secured on the spindle (notshown) of a metal-working machine or machine tool. The body 1 has a bore4- 'therethrough which is internally grooved adjacent its ends toreceive therein O-rings 5 and 6 or like packing rings of rubber-likematerial. Between said packing rings 5 and 6, the body 1 is undercut toform with the sleeve 7 an annular chamber 8 which is adapted to befilled with oil or grease or equivalent hydrostatic fluid as through thepassage 9 leading to said chamber 8.

When the chamber 8 has been filled with hydrostatic fluid, the passage 9may be closed as by means of the threaded plug 10. For the purpose ofapplying hydrostatic pressure on such fluid, the body 1 is formed withanother passage 11 leading from chamber 8 to the transverse passage 12,passage 12 having a plunger 14 with ,O-rings 15 or the like axiallyslidable therein. The end of the transverse passage 12 is internallythreaded to receive a socket head screw 16 which, when turned, bears onthe axially outer end of the plunger 14, thus to apply compressive forceon the hydrostatic fluid to effect deformation of the sleeve 7 in amanner now to be described in detail.

The sleeve 7 aforesaid in the form of the invention illustrated in FIGS.1, 2, and 3 has an integral flange 17 which is bolted to the end of thebody 1, the sleeve 7 extending through substantially the entire lengthof the bore 4 of the body 1 so that its end portions are in sealedengagement with the O-rings 5 and 6. Bolted in a counterbore in theother end of the body 1 is a collar member 18 which has a tapered orfrusto-conical lip 19, preferably of 60 included angle, which matchesthe correspondingly internally beveled or countersunk end 20 of thesleeve closely axially adjacent the O-ring 5. To facilitate insertion ofthe article A in sleeve 7 the entrance may be slightly tapered as at 22.

In the present case, by way of example only, the workpiece, tool holder,or other article A, has an elongated shaft portion 21 which is a closefit in the bore 23 of the sleeve 7 and which is of substantial length toextend throughout substantially the entire length of the sleeve 7.Adjacent the shaft portion 21 is a gear portion 24 having a shoulder 25adapted to abut the end of the sleeve 7.. For locking the article Aagainst turning with respect to the chuck there is mounted on the body 1a collar member 26 having internal teeth 27 matching those of thearticle A to be gripped.

To firmly grip said article A after it has been inserted as shown inFIG. 1, all that is necessary to do is to turn the socket head screw 16to cause the plunger 14 to advance toward the right as viewed in FIG. 2,whereupon, pressure is applied on the hydrostatic fluid. In this case,the pressure built up in the hydrostatic fluid causes radial inwarddeformation of the wall of the sleeve 7 into firm and accurate grippingengagement around a substantial and major portion of the length of theshaft portion 21 of article A. To prevent the possibility of excessivepressure being built up in the hydrostatic fluid, it is to be noted thatthe socket head screw 16 has limited travel in the transverse passage12.

By way of example, it has been found that in the case of a steel sleeve7 of .070 wall thickness and having a 3 bore 23 therethrough of 2.1255"diameter, for gripping the shaft portion 21 of an article A of 2.125diameter, the applicationof a pressure of 3,000 psi. on the hydrostaticfluid results in no measurable contraction of the sleeve 7 within theO-rings 5 and 6-, which in this ex,- ample were spaced about 2%".However, at this pressure and without an article A within the sleeve 7,said sleeve was deformed to uniform diameter of 2.1215" for about /3 ofits length midway between the O-rings 5 and 6. This is most clearlyshown in FIG. 3 in which the diameter of sleeve 7 at B and C remained at2.1255" and decreased to 2.1215" throughout the length D when thepressure of the fluid in chamber 8 was 3,000 p.s.i.

Accordingly, when the sleeve 7 is deformed as aforesaid, even without anarticle A therewithin, there is no deformation thereof within theO-rings 5 and 6 and thus no leakage of the hydrostatic fluid can occurbetween the body 1 and sleeve 7 joints. Of course, when the shaftportion 21 of 2.125" diameter is inserted into the sleeve 7, it will befirmly, uniformly, and stably gripped by the sleeve 7 throughout therelatively great axial length D even when the pressure on thehydrostatic fluid is less than the 3,000 p.s.i. indicated in theaforesaid example.

When it is desired to release the article A, the socket head screw 16 isturned to move it toward the left as viewed in FIG. 2, whereupon thesleeve 7 springs back to the original inside diameter of bore 4 and thehydrostatic fluid expands to move the plunger 14 toward the left.

Referring to FIG. 4, both ends of sleeve 7' are inter-- nally beveled asat to match the tapered lips 19 of the separate collar members 18 whichmay be identical with the collar member 18 shown in FIGS. 1 and 3. Themembers 18 are preferably harder than sleeve 7' to provide strong,non-deformable lips 19 and to resist wear and deformation due toinsertion and withdrawal of workpieces.

In FIG. 5, there is shown another arrangement of plunger mechanism toaid in filling of the chuck with hydrostatic fluid. Thus, with plungerand screw 31 in fully retracted position, and with screw 32 removed, thechuck may be filled through passage 9 (see FIG. 1) and excess fluidbeyond seat 34 is displaced through the filling passage 9 (pipe plug 10loosely inserted to permit leakage) as the screw 32 is brought intoengagement with seat 34. Thereafter pipe plug 10-is fully tightened toseal the fluid in the chuck.

FIG. 6 is similar to FIG. 1 except that the O-rings 5 and 6 are disposedin external grooves formed in the sleeve itself thus to eliminateundercutting operations in the body 41. Likewise, the grease or oilchamber 42 is defined by a long peripheral groove in the sleeve 40. Thecollar member 18 having the lip 19 engages in the tapered mouth 20 inthe sleeve 40 to support the latter although it is strengthened due toradial thickening adjacent the packing ring grooves.

While in FIGS. 1 to 6, the pressure on the grease or oil radiallycontracts the thin-walled sleeve it is to be understood that the sleevesmay be arranged reversely Iorradial expansion by such fluid pressure.Such an expansible arbor or mandrel is illustrated in FIG. 7

wherein a flanged sleeve 45 is secured to the body 46 as by screws 47,the long, thin-walled portion 48 of said sleeve surrounding the groove49 of the reduced extension 50 of said body 46. Leakage of fluid isprevented as by O-rings 51 and 52 which are sealed between the body 46and sleeve 45 adjacent radially thickened rigid zones of the latter sothat substantially no expansion occurs thereat to cause leakage. In FIG.7 pressure is applied on the grease or oil by turning the screw 53 whichbears on plunger 54. The plug 55 and plunger 56 is for venting whenfilling the arbor assembly.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equivalent ofsuch, be employed.

We therefore particularly point out and distinctly claim as ourinvention:

1. A hydrostatic chuck comprising a chuck body and a metalworkpiece-gripping sleeve telescopically interfitting one within theother and defining therebetween a chamber of substantial axial lengthadapted to be filled with a non-compressible fluid; packing ringsradially squeezed between said body and sleeve adjacent the ends of saidchamber effective to seal the body-sleeve joints the'reat; said bodyhaving a passage leading to said chamber; said sleeve between saidpacking rings being relatively thin and of uniform radial wall thicknessso as to be radially deformed to grip a workpiece upon supplying fluidpressure to said chamber; and a collar member secured to said body inradially and axially overlapped relation with one end of said sleeveaxially adjacent the corresponding packing ring for maintaining said oneend in engagement with said chuck body thus to preclude radialdeformation of said sleeve thereat.

2. The chuck of claim 1 further comprising a' plunger in said passage;means for moving said plunger in said passage to build up pressure inthe fluid filling said passage and chamber tending to enlarge radiallythe latter; a second passage leading to said chamber and having a plugtherein which is adapted to be removed for filling said chamber andfirst-mentioned passage with fluid; and a second plug in saidfirst-mentioned passage which is adapted to be removed to facilitatefilling of said chamber and first-mentioned passage through said secondpassage.

3. The chuck of claim 1 wherein said sleeve at its other end axiallyadjacent the other packing ring has an integral radially extendingflange secured to said body thus to preclude radial deformation of saidsleeve thereat.

4. The chuck of claim 1 wherein said sleeve has an internally beveledend portion axially adjacent the corresponding packing ring; and saidcollar member has an externally beveled lip in mating engagement withinthe internally beveled end of said sleeve thus to preclude radialdeformation of said sleeve thereat.

5. The chuck of claim 1 wherein each end of said sleeve is internallybeveled adjacent the corresponding packing rings; and two of said collarmembers are secured to said body adjacent the ends of said sleeve, eachcollar member having an externally beveled lip in engagement with theadjacent internally beveled end of said sleeve thus to precludedeformation of said sleeve thereat.

6. A hydrostatic chuck comprising a chuck body; a metalworkpiece-gripping sleeve telescopically interfltting inside said chuckbody and defining with the latter a chamber of substantial axial lengthadapted to be filled with a non-compressible fluid; packing ringsradially squeezed between said body and sleeve effective to seal thebody-sleeve joints adjacent the ends of said chamber; said body having apassage leading to said chamber; a plunger movable in said passage tobuild up pressure in the fluid filling said passage and chamber tendingto enlarge radially the latter, said sleeve between said packing ringsbeing relatively thin and of uniform radial wall thickness so as to beradially contracted to grip a workpiece therewithin upon movement ofsaid plunger; and a collar member secured to said body in radially andaxially overlapped relation 'with one end of said sleeve axiallyadjacent the corresponding packing ring for 'maintaining said one end inengagement with said body thus to preclude radial deformation of saidsleeve thereat.

7. The chuck of claim 6 wherein said sleeve at its other end axiallyadjacent the other packing ring has an integral radially extendingflange secured to said body thus .to' preclude radial deformation ofsaid sleeve thereat.

8. The chuck of claim 6 wherein said sleeve has an internally beveledend portion axially adjacent the corresponding packing ring; and saidcollar member has an externally beveled lip in mating engagement Withinthe internally beveled end of said sleeve thus to pre elude radialdeformation of said sleeve thereat.

9. The chuck of claim 6 wherein both ends of said sleeve are internallybeveled adjacent the corresponding packing rings, and there is a collarmember secured to said body adjacent both ends of said sleeve, eachcollar member having an externally beveled lip in engagement With theadjacent internally beveled end of said sleeve thus to precludedeformation of said sleeve thereat.

References Cited by the Examiner UNITED STATES PATENTS Teetor 279-4Atherholt 2794 Williams.

Van Roojen 279 4 Drantz 279--4

1. A HYDROSTATIC CHUCK COMPRISING A CHUCK BODY AND A METALWORKPIECE-GRIPPING SLEEVE TELESCOPICALLY INTERFITTING ONE WITHIN THEOTHER AND DEFINING THEREBETWEEN A CHAMBER OF SUBSTANTIAL AXIAL LENGTHADAPTED TO BE FILLED WITH A NON-COMPRESSIBLE FLUID; PACKING RINGSRADIALLY SQUEEZED BETWEEN SAID BODY AND SLEEVE ADJACENT THE ENDS OF SAIDCHAMBER EFFECTIVE TO SEAL THE BODY-SLEEVE JOINTS THEREAT; SAID BODYHAVING A PASSAGE LEADING TO SAID CHAMBER; SAID SLEEVE BETWEEN SAIDPACKING RINGS BEING RELATIVELY THIN AND OF UNIFORM RADIAL WALL THICKNESSSO AS TO BE RADIALLY DEFORMED TO GRIP A WORKPIECE UPON SUPPLYING FLUIDPRESSURE TO SAID CHAMBER; AND A COLLAR MEMBER SECURED TO SAID BODY INRADIALLY AND AXIALLY OVERLAPPED RELATION WITH ONE END OF SAID SLEEVEAXIALLY ADJACENT THE CORRESPONDING PACKING RING FOR MAINTAINING SAID ONEEND IN ENGAGEMENT WITH SAID CHUCK BODY THUS TO PRECLUDE RADIALDEFORMATION ON SAID SLEEVE THEREAT.